Low-Cost and Rapid-Production Microfluidic Electrochemical Double-Layer Capacitors for Fast and Sensitive Breast Cancer Diagnosis

Abstract

This technical note describes a new microfluidic sensor that combines low-cost (USD $0.97) with rapid fabrication and user-friendly, fast, sensitive, and accurate quantification of a breast cancer biomarker. The electrodes consisted of cost-effective bare stainless-steel capillaries, whose mass production is already well-established. These capillaries were used as received, without any surface modification. Microfluidic chips containing electrical double-layer capillary capacitors (μEDLC) were obtained by a cleanroom-free prototyping that allows the fabrication of dozens to hundreds of chips in 1 h. This sensor provided the successful quantification of CA 15-3, a biomarker protein for breast cancer, in serum samples from cancer patients. Antibody-anchored magnetic beads were utilized for immunocapture of the marker, and then, water was added to dilute the protein. Next, the CA 15-3 detection (<2 min) was made without using redox probes, antibody on electrode (sandwich immunoassay), or signal amplification strategies. In addition, the capacitance tests eliminated external pumping systems and precise volumetric sampling steps, as well as presented low sample volume (5 μL) and high sensitivity using bare capillaries in a new design for double-layer capacitors. The achieved limit-of-detection (92.0 μU mL) is lower than that of most methods reported in the literature for CA 15-3, which are based on nanostructured electrodes. The data shown in this technical note support the potential of the μEDLC toward breast cancer diagnosis even at early stages. We believe that accurate analyses using a simple sample pretreatment such as magnetic field-assisted immunocapture and cost-effective bare electrodes can be extended to quantify other cancer biomarkers and even biomolecules by changing the biorecognition element.

Rheology of the Electric Double Layer in Electrolyte Solutions

“…When a charged surface is immersed in an electrolyte solution, dissolved ions are assembled on it, and an electric double layer (EDL) is formed at the solid–liquid interface to screen the charge of the surface. − The EDL therefore plays a crucial role in various biological and industrial processes, such as biosensing, − enzymology, − coatings, , and storing energy in batteries. ,− The electrostatic screening mechanism and the resulting properties, such as double layer capacitance and shear viscosity, of the EDL are well understood at low ion concentrations. On the other hand, today’s ever-growing activities in biotechnology and new energy development have led to an increasing need for understanding the EDL behavior in concentrated electrolyte solutions, such as ionic liquids (ILs) .…”

Application of Microfluidic Systems for Breast Cancer Research

“…DEP-isolation of CTCs is independent of cell surface markers, and the isolated CTCs are viable and can be maintained in culture [162]. Low-cost and rapid-production microfluidic electrochemical double-layer capacitors have enabled fast and sensitive breast cancer diagnosis using the dielectric properties of CTCs [163]. Magnetic sorting using magnetic beads has become a routine methodology for the separation of key cell populations from biological suspensions.…”

Recent Advancement for the Synthesis of MXene Derivatives and Their Sensing Protocol

“…Standard serum PSA levels are less than 4.0 ng mL -1 in healthy males, whereas increasing serum PSA levels are related to prostate cancer contents. [222,223] During the last decade, different strategies were developed to detect PSA trace contents in the human body.…”